Adenine compounds such as adenine, adenosine, and phosphoric esters of adenosine are known to have various useful effects, such as skin pigmentation reduction and skin-aging prevention, and are used as an active ingredient in compositions for external application. Examples of known compositions containing an adenine compound include an O/W emulsion composition (see Patent Document 1) and a solid composition comprising an oil-in-water emulsion (see Patent Document 2).
The composition for external application to the skin in the form of an adhesive patch is required to have a good adhesion to the skin and provide a comfortable feel when used, in addition to eliciting a desired effect from the active ingredient. However, there has been no report of an adenine compound-containing composition for external application to the skin in the form of an adhesive patch that is satisfactory in terms of all of: elicitation of useful effects from an adenine compound; adhesion to the skin; and comfortable feel when used.
Furthermore, there is no known product for external application containing a gel composition for external application immersed in an aqueous solution containing an active ingredient. What properties are imparted to the gel composition for external application provided in such an immersed state are also unknown.
With the recent trend toward more diverse and advanced physiological effects required of compositions for external application under the above-mentioned background of the prior art, there has been a demand for the development of a composition for external application in a form capable of eliciting useful effects from an adenine compound more effectively and sustainably.    Patent Document 1: Japanese Unexamined Patent Publication No. 2002-234830    Patent Document 2: Japanese Unexamined Patent Publication No. 2006-182746